Collapsible boom for mobile cranes



April 3, 1962 A. H. MOTT 3,028,018

COLLAPSIBLE BOOM FOR MOBILE CRANES Filed May 8, 1959 2 Sheets-Sheet 1INVENTOR AHMA i2 M ATT NEY April 3, 1962 A. H. MOTT 3,028,018

LLAPSIBLE BOOM FOR MOBILE CRANES Filed May 8, 1959 2 Sheets-Sheet 2 ANEY United States Patent Ofitice 3,028,1il8 Patented Apr. 3, 19623,028,018 COLLAPSIBLE BOOM FOR MOBILE CRANES Alfred H. Mott, 73 PaisleyAve. S., Hamilton, Ontario, Canada Filed May 8, 1959, Ser. No. 811,996 1Claim. (Cl. 212-59) The present invention generally relates to a boomconstruction and more particularly to a foldable and collapsible boommounted on a mobile vehicle.

The primary object of the present invention is to provide a crane havinga main boom and a jib pivotally attached to the outer end thereof inwhich the jib boom is foldable to a position alongside the main boomwith the main boom including upper and lower half booms pivotallyinterconnecting, which may be maintained in rigid aligned relation orfolded to side by side condition.

The present invention overcomes the problems of an elongated boom andjib in over the road transportation. It is extremely difiicult tomaneuver an elongated boom when the carrying vehicle is driven on theroad, and this boom also presents a danger to other motorists since theboom extends quite a distance in front of or rearwardly of the vehicle.If the boom is disassembled for transportation, quite a number of hoursare required to disassemble the boom and then re-assemble it at the joblocation. Therefore, the present invention not only saves time and laborbut also provides a safer manner of moving a crane. With the presentinvention, the boom can be easily folded to collapsed condition orextended in a minimum time while requiring only one operator although itis preferable to have one man in the control cab while another man is onthe ground to handle certain portions of the structure.

A further object of the present invention is to provide a foldable boomand jib which are relatively simple in construction, easy to fold andunfold, safe in operation, long lasting, dependable, and relativelyinexpensive to manufacture and maintain.

Still other objects and advantages will appear from the followingdescription of an exemplifying embodiment of this invention, from theappended claim and from the accompanying drawings:

FIGURE 1 is a side elevational view of the crane illustrating the mainboom and jib boom in operative position;

FIGURE 2 is a partial side elevational view illustrating the first stepin the folding procedure;

FIGURE 3 is a view similar to FIGURE 2 and illustrating the second stepin the folding procedure;

FIGURE 4 is a view similar to FIGURE 2 and illustrating the third stepin the folding procedure;

FIGURE 5 is a view similar to FIGURE 2 and illustrating the final stepin the folding procedure;

FIGURE 6 is a side elevational view of the crane with the main boom andjib boom in folded or collapsed condition;

FIGURE 7 is a fragmentary perspective view illustrating the connectionbetween the halves of the main boom; and

FIGURE 8 is a fragmentary perspective view of the jib boom and itsconnection to the upper end of the main boom.

Referring now specifically to the drawings, the numeral 10 generallydesignates the crane including a mobile vehicle 12, a main boom 14 and ajib boom 16 attached to main boom 14.

The vehicle 1-2 includes the usual cab 18 housing the power mechanismand controls therefor. The cab 18 is rotatable about a vertical axis andis self propelled by virtue of the power driven crawler treads 20, allof which may vary and the details of this structure form no particularpart of the present invention.

The main boom 14 is hingedly supported from the frame 22 of the cab 18for vertical swinging movement by hinge pin 24. The main boom is alsoconstructed of an upper half boom 26 and a lower half boom 28, each ofwhich includes corner rails 30 rigidly interconnected by braces 32 whichform a skeletonized boom which tapers from the center of the boomtowards a narrower and shallower configuration at the remote endsthereof.

The lower pair of rails 30 have brackets 34 on their adjacent ends whichare hingedly interconnected by pivot shaft 36 which extends between thelower rails 30 and carries a supporting prop or leg 38 which isswingable from a position lying alongside of the boom to a positiondepending therefrom.

The upper pair of corner rails 30 have brackets 40 which overlap and areprovided with removable lock bolts 42,. The lock bolts 42 are notnecessary to the operation of the device and are employed as an addedsafety precaution. Each half boom 26 and 28 is provided with a roller 44journaled between the upper pair of rails 30 for forming cable engagingrollers under certain conditions as set forth hereinafter.

At the outer end of the upper half boom 26, there are provided gussets46 journaling a shaft 47 carrying pulleys 48 and 50 thereon with thegussets 46 also having upstanding brackets 52 rigidly afiixed theretofor pivotally supporting the jib boom 16.

The jib boom 16 includes corner rails 54 interconnected by braces 56with the inner ends of rails converging and rigidly secured together bygussets 58. The outer ends also converge and are interconnected bygussets 60. The inner gussets 58 are interconnected by a transverseshaft 62 which also extends through the upper ends of brackets 52 inspaced relation to the pulleys 48' and 50.

Pivotally attached to the gussets 58 by hinge pin 63 are two upwardlyextending support posts 64 and 66 rigidly interconnected by a crossedbrace member 68. Extending between the posts 64 and 66 is a shaft 70having a cable pulley or sheave 72 mounted thereon. Also, the upper endsof the posts 64 and 66 are provided with cable seats for receiving bracecables 74 having one end thereof connected to the upper frame rails 54adjacent the outer end thereof and having the other end connected to theupper rails 30 of the upper half boom 16 adjacent the inner end thereoffor forming the tension member of the truss formed when the boom and jibboom are in operative position.

The outer gussets 60 are interconnected by a shaft 76 receiving a cablepulley 78fithereon. A cable 80 passes over pulley 78 and extendsdownwardly and terminates in a load carrying hook 82. Cable 80 alsopasses over pulley 72 and extends rearwardly into the cab for attachmentto a suitable winch mechanism for raising and lowering a load carried byhook 82. When the main boom and jib are folded, the cable 80 will rideon the rollers 44 to prevent damage to the cable. A boom cable 84extends over pulley 48 which also has a hook 86 on the free end thereof.Pulley 50 is not employed unless the jib boom is not used, then jibcable 80 is entrained over pulley 50. The main boom is raised andlowered by the boom support cables 33.

In order to fold the boom, the hooks 82 and 86 are fastened to the jibboom 16 and lower half boom 28 respectively and the boom is lowereduntil the depending leg 3-8 strikes the ground. Assuming that no lockbolts interconnect brackets 40, the upper half boom 26 may continue tolower until the jib boom and the outer end of the upper half boom areresting on the ground as shown in FIGURE 3. Then the lower half boom 28is raised while the upper half boom 26 and the jib 16 stay on the groundas shown in FIGURE 4. The support posts 64 and 66 fold down due to theirown weight. The lower half boom 28 is raised further and the upper halfboom 26 is pulled towards the cab 18 as shown in FIGURE 5 and the jibstarts to fold back against the upper half boom 26. FIGURE 6 shows thefinal folded position of the boom and the boom is unfolded by followinga reverse sequence of steps. When the upper and lower half booms are inalignment, the overlapping brackets 40 and the hinged brackets 34 abuteach other in such a manner that pivotal movement in only one directionis permitted and as long as lifting force is exerted on the outer end ofthe boom, the half booms will be maintained in rigid alignment.

It is understood that this invention is not confined to the particularembodiment shown and described, the same being merely illustrative, andthat this invention may be carried out in other ways within the scope ofthe appended claim without departing from the spirit of this invention,as it is obvious that the particular embodiment shown and described isonly one of the many that may be employed to attain the objects of thisinvention.

I claim:

A boom assembly for cranes comprising an elongated main boom, a jib boompivotally mounted on the outer end of said boom, truss meansinterconnecting the main boom and jib boom comprising collapsibleupwardly extending support posts at the inner end of said jib boom andbrace cables extending over the tops of said support posts and connectedbetween the outer end of said jib boom and the mid portion of said mainboom to support said jib boom in extended position from the outer end ofsaid main boom, whereby the jib boom may be folded over upwardly to aposition alongside the main boom, said main boom including an upper halfboom and a lower half boom pivotally interconnected inwardly of said midportion for swinging movement of the upper.

half boom in a downward direction in relation to the lower half boom,and stop means at said interconnection for preventing upward swingingmovement of the upper half boom above a position in alignment with thelower half boom, thereby maintaining the half booms in align- .4 mentwhen the main boom is supported from the outer end of the upper halfboom, a pivotal prop mounted at the pivotal connection between the halfbooms for swinging movement from a depending operative position to aninoperative position alongside one of the half booms, said prop adaptedto support the connection between the half booms in elevated positionabove a supporting surface, thereby enabling the jib boom and the outerend of the upper half boom to rest on such a supporting surface wherebythe outer end of the lower half boom may be elevated for swinging theupper half boom to a downwardly extending position alongside theundersurface of the lower half boom, said main boom and jib boom beingof skeletonized construction and include longitudinal corner railsinterconnected by-braccs, said corner rails converging at the endsthereof and being interconnected by gusset plates, a cable pulley moutedon the outer end of the jib boom and on the outer end of the main boom,a jib boom load cable entrained over the pulley on the jib boom, a loadcable entrained over the pulley on the main boom, hook means on theouter end of each cable adapted for attachment to a load and forattachment to a portion of the boom assembly for holding the assembly infolded condition, said lower half boom and the upper half boom eachhaving a transverse roller journalled thereon adjacent the point ofpivotal connection therebetween for engaging the load cables when thehalf booms are moved to a folded position.

References Cited in the file of this patent UNITED STATES PATENTS885,803 Terry Apr. 28, 1908 1,920,370 Forsythe Aug. 1, 1933 2,073,539Shelton Mar. 9, 1937 2,772,790 Kauffman Dec. 4, 1956 FOREIGN PATENTS519,605 Italy Mar. 15, 1955 737,302 Great Britain a Sept. 21, 1955849,605 Germany Sept. 15, 1952 1,036,452 1 France Apr. 22, 1953

